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Photographic 

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1 

2 

3 

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5 

6 

GENERAL    SERRELL'S    REPORT 


ON  THE  LOCATION  OF^THE 

Hudson  HigMand  Suspension  Bridge. 


►••♦>< 


CHIEF  ENGINEERS'  OFFICE,       '^ , 

^nimn  M^Mmnl  ^mpn^im  grldlgr, 

JVew   York,  Avffust  Wh,  1868.      . 

To  the  Exe&utive  Committee.  . 

Gentlemen:  '''^.,  ■.'"' 

In  compliance  with  your  resolution  of  the  l?t]i  June,  direct- 
ing the  Chief  Engineer  to  tabulate  the  facts  at  the  differ- 
ent proposed  crossings,  particularly  with  i-eference  to  the 
approaches,  in  order  that  the  board  may  with  precision  select 
ihe  very  best,  I  have  the  honor  to  submit  herewith  a  tracing 
of  the  primary,  and  secondary  tnangulations,  and  other  meas- 
urements made  on  the  ground,  and  compiled  from  surveys 
previously  made,  together  with  such  calculations,  and  other 
data,  as  will,  I  believe,  comply  with  your  instnictions,  and 
enable  you  to  decide  where  the  best  location  for  the  bridge  is  to 
be  found. 

In  making  these  examinations,  I  have  been  governed  solely 
by  the  facts,  as  they  are  found  on  the  ground,  and  I  am  greatly 
indebted  to  the  United  States  Coast  Survey  c»ffice  for  '.ndlateral 
valuable  information  furnished. 

By  the  first  section  of  ihe  act  incor|)orati!ig  the  company, 
chapter  333  of  the  laws  of  1868,  you  are  authorized  "to  construct 
and  maintain  a  permanent  Bridge,  appurtenances,  and  avenues 
of  approach  thereto  for  the  passage  and  transportation  of  passen- 
gers, railroad  trains,  vehicles,  cattle,  liorses,  &c.,  &c.  to,  and 
from  the  east,  and  west  banks  of  the  Hudson  River,  at  some 
point,  or  points  between  Verplanck's  Point  and  Buttermilk 
Falls  on  said  river." 


} 


r< 


"VerplMick's  Point  and  Buttermilk  Falls,  are  about  ten  mile* 
apart,  and  within  this  whole  included  space,  all  the  shore  lines 
have  been  traced,  and  at  every  position  having  the  appearance 
of  offering  such  facilities  for  crossing  the  Hudson  River  by 
Bridge,  as  you  require,  minute  measurements  have  been  made. 

Very  nearly  all  the  crest  lines  have  been  run  out  on  both 
Bides  of  the  River, and  contours  traced  to  afford  minute  informa- 
tion of  the  topography. 

In  addition  to  such  surveys  as  seemed  necessary  to  ascertain 
the  best  position  for  the  Bridge,  considered  as  an  independent 
structure,  measurements  have  been  made,  lines  run,  and  cross- 
sections  taken  to  give  you  all  required  information,  respectinrj  the 
proposed  avenues  of  approach,  highways  leading  to  the  Bridge, 
and  particularly  having  in  mind  the  great  system  of  railways 
leading  to,  and  frtom  your  work,  very  accurate  information  has 
been  obtained  by  actual  survey,  showing  the  grades  and  align- 
ments of  various  routes,  practicable  and  impracticable,  reaching 
the  different  sites  of  the  Bridge,  upon  which  estimates  have 
been  made. 

Witl'^u  the  limits  authorized  by  law,  over  which  you  are 
allowed  to  cross  the  river,  the  water-way  varies  in  width  from 
less  than  five  hundred  yards  to  over  a  mile  and  a  quarter. 

The  location  is  in  the  beautiful  and  grand  highlands,  classical 
and  historic,  far  lovelier  than  any  portion  of  the  Rhine,  bolder, 
and  more  distinct  in  its  character  than  any  part  of  the  valley  of 
the  Father  of  Waters. 

Topographically  the  region  may  be  described  as  mountainous. 

At  the  southwesterly  portion  of  the  district  stands  the*"Dun- 
derberg,"  towering  to  a  height  of  1650  feet  above  the  river.  This 
mountain  breaks  down  to  the  westward  near  to,  and  connects 
with  "  Bear  Hill "  to  the  north  of  which  is  "  Popolopen"  Creek, 
the  head  waters  of  which  are  not  far  from  the  celebrated  "Forest 
of  Dean"  iron  mines. 

Northerly  of  Popolopen,  is  the  "  Torn  Mountain,"  which 
is  more  or  less  distinctly  defined,  as  it  occupies  the  Westerly 
Slope  ot  the  Valley  of  the  Hudson  for  some  six  miles,  and  then 
is  merged  into  "Crow's  Nest,"  to  the  rear  of  the  Military  Post 


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of  West  Point.  This  range  is  however  broken  through  by  the 
secondary  valley,  in  which  is  Buttermilk  Falls.  South  of  Popo- 
lopen  there  is  a  table-land,  about  one  hundred  and  fifty  feet 
high,  triangular  in  form,  about  one  mile  and  a  half  in  length, 
and  a  mile  wide  at  the  northerly  end. 

The  shores  of  the  River  at  the  Dunderburg,  are  in  most 
places  precipitious :  and  this  is  their  character  all  the  way  to  the 
southward  from  the  table-land  before  described  as  far  as  your 
assigned  limits  extend.  ■    ' 

North  of  the  Popolopen  and  between  the  river  and  the 
Torn  Mountain,  there  is  a  plain  of  nearly  the  same  elevation 
as  that  south  of  the  stream  and  this  extends  with  more  or  less 
distinctness  to  Buttermilk  Falls.  At  the  river  south  of  Popo- 
lopen, the  locality  is  called  Fort  Clinton,  and  north  of  the  creek 
Fort  Montgomery,  both  of  them  localities  of  revolutionary 
note,  and  being  among  the  initial  points  are  frequently  referred 
to,  in  this  communication. 

A  locality,  known  as  Doodletown  is  situated  on  the  northerly 
side  of  the  Dunderberg  between  it  and  Bear  Hill,  here  the 
drainage  of  the  country  forms  a  little  brook:  except  Popolopen 
this  is  the  only  considerable  stream  on  the  westerly  side  of  the 
river  within  our  included  space. 

On  the  easterly  bank  of  the  Hudson,  directly  opposite  Fort 
Clinton,  is  a  bold  promontory  known  as  "  St.  Anthony's  Nose." 
This  is  very  abrupt  at  the  water-line,  and  the  Hudson  River 
rail-road  tunnels  the  point. 

The  Mountain  is  reported  from  various  sources  to  be  from 
1228  to  1418  feet  in  bight.  For  your  purposes,  it  was  not  con- 
sidered "necessary  to  ascertain  the  altitude.  The  mountain  form- 
ing the  continuation  of  the  promontory  is  very  well  defined,  of 
bold  distinct  outline,  without  any  very  decided  passes,  except  one 
very  high  onCf  through  which  the  wagon  road  from  Peekskill 
to  Garrison's  passes. 

The  general  direction  of  the  range  is  north-east,  and  south- 
west, and  it  rises  to  a  crest  line  of  several  miles  in  lengtli,  forming 
an  angle  with  the  general  direction  of  the  Hudson  river  of  some 
forty  degrees. 


The  general  direction  of  the  Valley  of  the  Hudson  is  due 
north  and  south,  although  below  "  St.  Anthony's  Nose,"  the 
tend  is  to  the  eastward,  say  south-east,  for  some  three  or  four 
miles,  and  north  of  the  "Nose,"  north-easterly  some  four  or  five 
miles. 

Directly  above  the  "  Nose"  the  shore  of  the  river  is  low,  and 
marshy,  for  some  three  hundred  yards,  or  more,  above  this, 
there  is  a  terrace,  and  this  is  some  one  hundred  and  forty,  to  one 
hundred  and  sixty  feet  high ;  and  extends  to  the  water's  edge 
with  abrupt  precipitous  cliffs  of  rock,  nearly  all  the  way  to  Gar- 
rison's Landing  which  is  just  above  Buttermilk  Falls,  and  on 
the  opposite  side  of  the  river. 

Above  this  plain  on  the  river,  and  opposite  Buttermilk  flails, 
and  to  the  eastward  of  the  plain  just  described  is  the  hill,  known 
as  "  Sugar  Loaf,"  one  of  the  most  prominent  features  of  the 
landscape.  This  is  a  conical  mountain  on  its  east  and  west 
section,  and  serves  as  a  good  point  of  reference. 

In  the  wide  part  of  the  river  opposite  the  intersection  of  the 
Dunderberg  and  Bear  Hill,  and  in  front  of  Doodletown 
is  "Grant's  or  "  Ionia  Island",  containing  some  120  acres,  and 
immediately  below  is  "Round  Island,"  containing  10  acres. 

South  of  Buttermilk  Falls  on  the  westerly  side  of  the  river, 
there  is  a  rocky  promontory  separated  from  the  main  shore  by  a 
salt  marsh,  the  place  is  known  as  "Consute,"  or  "  Marsh  Island." 

It  is  really  not  an  Island  at  all,  being  connected  with  the 
bluffs  of  the  river  side  by  a  passable  rocky  marsh,  covered 
with  sedge. 

The  high  table  laud  south  of  West  Point,  and  east  of  the 
Torn  Mountain,  extends  to  Fort  Montgomery,  but  is  ^^roken 
through  by  a  ridge  of  granite  at  Cozzens.  It  contains  about 
700  acres,  south  of  the  northern  limits  of  your  location  at  an 
elevation  of  from  one  hundred  and  fifty,  to  one  hundred  and 
sixty  feet  above  tide. 

The  similar  plateau  below  the  Popolopen  Creek  containis  ibout 
one  hundred  and  thirty  acres,  exclusive  of  the  Beautiful  sheet  of 
water,  known  as  "Highland  Lake,"  which  is  some  half  a  mile 
long,  and  two  hundred  yards  wide,  and  is  at  an  elevation  of 
about  one  hundred  and  forty  seven  feet  above  tide. 


Y 


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On  the  easterly  side  of  the  river,  south  of  your  northern  hmita, 
the  plateau  contains  about  three  hundred,  and  twenty-five  acres, 
and  this  plain  extends  to  the  north  some  miles,  at  nearly  the 
same  elevation  that  the  corresponding  Bench  has  on  the  opposite 
side.  That  is,  it  varies  in  hight  from  one  hundred  and  forty,  to 
one  hundred  and  seventy  feet  above  tide,  and  is  broken  through 
by  a  small  stream,  nearly  opposite  the  south  end  of  Consute 
Island. 

To  the  westward  of  Round  Island,  Ionia  and  Consute 
respectively,  the  rocks  are  joined  to  the  right  bank  of  the  river 
by  river  deposits,  forming  marshes,  and  northerly  of  St.  An- 
t'lony's  Nose  on  the  left  bank,  there  is  a  triangular  marsh  of 
the  same  character. 

There  are  also,  some  small  swanijis  on  the  margin  of  the  river 
in  the  rocky  coves,  most  of  which  coi^ain  from  a  few  hundred 
square  feet  to  say  half  an  acre. 

Southerly  from  St.  Anthony's  Nose,  on  the  easterly  side  of 
the  river,  the  mountain  is  parallel  to  the  water-course,  and  very 
steep,  rocky  and  abrupt  for  over  a  mile.  It  is  then  broken  into, 
by  a  small  secondary  valley,  and  again  rises  to  a  great  elevation, 
a  portion  of  the  distance  being  almost  vertical. 

Opposite  to  Eound  Island,  there  is  another  nose,  and  from 
this,  the  face  of  the  cliff  tends  to  the  south  east,  leaving  the  river 
between  which  and  the  mountain,  there  is  an  elevated  plain, 
with  some  hills  upon  it ;  the  most  southerly  part  is  called  "Roay 
Hook." 

Peekskill  Creek  hollow  breaks  into  the  north  eastward,  be- 
low the  point,  and  at  its  confluence,  with  the  Hudson,  the  valley 
is  half  a  mile  wide,  or  more. 

The  stream  is  tide  water  for  a  mile  or  so,  to  where  the  Anns- 
ville  Creek  intersects  it ;  this  latter  comes  from  the  hills  of 
Putnam  County,  and  has  a  bed  upon  a  high  angle  of  inclina- 
tion. 

Southerly  towards  Verplank's  Point  from  Peekskill  Creek, 
and  Annsville  Stream  the  country  is  a  very  irregalar  plain, 
eloping  from  the  Hudson  to  an  elevation  of  about  one  hundred 
and  sixty  feet  high,  where  it  spreads  out  into  a  general  level,  up- 
on which  is  built  the  fine  village  of  Peekskill. 


There  is  through  this  plane  a  stream  affording  fine  water 
priyileges.  Still  further  to  the  south,  the  land  is  high,  and  ir- 
regular. 

The  Hudson  River  at  Peekskill  is  over  a  mile  and  a  quarter 
wide,  and  the  landing  places  are  in  a  deep  bend,  almost  an  el- 
how.  The  Dunderberg  forms  the  salient  of  the  right  bank 
directly  opposite. 

Geologically  the  region  should  be  considered  as  composed  of 
primitiye  rocks,  although  there  are  some  detached  limestones  in 
yeins  and  masses. 

Quantities  of  iron  exist  combined  witli  feldspar  and  sulphur, 
and  this  enters  largely  into  the  discussion  of  suitable  anchorage 
gronnd:  green  stone  in  scams,  and  some  hornblende  in  masses 
may  he  foand  scattered. 

There  are  some  segrega,^ed  seams  of  plumbago  in  the  de- 
tached limestones,  and  these  have  occasioned  much  reflection 
upon  the  probable  effect  of  the  rocks,  or  their  contained  alkalies 
upon  the  iron,  and  steel  of  the  Bridge. 

The  granite  of  which  most  of  the  district  consists,  varies 
Tery  much  in  character.  Some  is  solid,  and  compact  in  large 
blocks,  without  seama  of  any  kind,  blue,  or  whitish  in  color ; 
other  portions  are  cmoritic  and  of  irregular  fracture.  Some 
contain  an  excess  of  mica,  others  large   quantities  of  feldspar. 

have  not  seen  hornblende,  or  quartz  in  excess,  except  very  ir- 
regularly. 

The  very  best  granite  for  building  exists  but  the  quarries 
generally  have  not  been  opened. 

One  quarry  on  the  east  side  about  a  mile  above  St.  Anthony*s 
Nose,  has  had  some  fine  stoties  taken  out  of  it ;  the  quarries 
are  not  however  very  large,  at  least  such  stems  to  be  the  cas« 
from  present  appearances. 

South  of  Verplanck's  Point  on  the  opposite  side  of  the  river, 
there  are  some  very  valuable  lime  quarries,  but  no  stone  of  this 
kind  suitable  for  building.  There  is  at  this  locality  and  at  Roay 
Hook,  very  excellent  sand  for  cement  mortar  and  to  the  west 
of  Consute  Island  about  a  mile,  very  good  fine  gravel  and 
building  sand. 


Having  thus  endeavored,  to  give  you  some  faint  idea  of  the 
physical  chaructor  of  the  country  Burrounding  and  including 
the  region,  you  tire  authorized  hy  law  to  occupy,  for  a  crossing 
of  the  mighty  Hudson,  so  far  as  the  topography  and  geology 
arc  concerned,  lot  us  before  going  any  further,  enquire  for  a  mo- 
ment into  the  climate,  we  have  to  deal  with. 

Although  in.  the  mountains,  and  some  fifty  miles  from  the  sea, 
the  Hudson  River  is  for  the  greater  part  of  the  year  quite  salt  at 
this  place,  and  is  influenced  by  the  tides,  and  the  southerly  winds 
from  the  Bay  of  New  York,  and  the  Tappan  Zee  :  they  are  by  no 
means  what  we  usually  designate  upland  breezes.  They  are,  in 
fact,  almost  salt  air,  considered  with  reference  to  iron  struc- 
tures. 

The  thermal  range  is  very  great  in  the  Highlands  of  the  Hud- 
son, and  eijuals  one  hundred  and  sixty  degrees  Fahrenheit ; 
at  least  so  very  (ionsiderable  a  quantity  has  to  be  provided  for  in 
all  your  mechanism  for  compensating  expansions  and  contrac- 
tions due  to  this  cause. 

Snow  falls  in  great  quantities,  frequently  six  or  seven  feet 
deep  on  a  level,  and  in  the  drifts  many  times  this  amount, 
and  the  winds  are  frequent  and  severe.  I  have  been  enabled 
through  the  kindness  of  scientific  gentlemen  living  in  the 
neighborhood,  and  from  observations  made  during  many  years 
past,  by  order  of  the  government  to  obtain  valuable  information 
on  these  subjects.  The  quantity  of  rain,  and  snow  which  falls 
in  a  year  and  also  the  greatest  amount  that  has  accumulated  for 
many  years  part  is  recorded  ;  and  the  direction,  velocity,  and 
force  of  the  wind  at  different  places  in  the  vicinity  is  known. 

I  have,  however,  been  unable  as  yet,  to  collect  any  consider- 
able amount  of  reliable  information,  respecting  the  electrical,  or 
magnetic  phenomena  of  the  region,  and  but  little  seems  to  be 
known,  or  at  least  I  have  not  found  it  recorded ;  and  many 
meteorological  facts  which  should  be  well  understood  while 
building  such  a  large  and  important  work  as  you  contem- 
plate, have  not  been  collected,  apparently,  and  there  has  not  been 
sufficient  time  since  your  orders  were  given,  to  obtain  them  by 
a  series  of  personal  investigations. 

I  think  though,  you  may  now  rest  assured,  that  sufficient  in- 


i 


formation  has  been  obtained  of  the  topography,  geology,  and  cli- 
mate to  enable  you  to  form  an  intelligent  opinion,  and  como  to  a 
wise  and  reliable  judgment  in  determining  the  location  for  the 
Bridge. 

So  much  for  these  points ;  let  us  now  consider  analytically  the 
geometry  of  the  case. 

The  line  A.  A',  is  a  section  at  Round  Island.  It  begins  on  the 
northerly  face  of  the  Dunderberg  mountain,  at  an  elevation  of 
one  hundred  and  sixty  feet  above  tide,  and  crosses  to  a  projection 
of  the  southerly  face  of  the  prolongation  of  the  range,  forming 
at  tht  Kiver,  8t.  Anthony's  Nose,  and  passes  over  Round  la- 
land,  somewhat  to  the  south-ward  of  the  centre  of  the  island. 

At  an  elevation  of  one  hundred  and  fifty  feet  high  above  tide, 
level  grade  would  strike  the  natural  surface  at  two  points  on 
opposite  sides  of  the  river,  five  thousand  three  hundred  and 
Bev3nty-two  feet  (5372)  apart. 

Round  Island  is  about  ninety  five  feet  high,  at  the  highest 
point  above  high  water  and  affords  facilities  for  a  tower  and 
foundations,  bui  is  not  wide  enough  in  the  direction  of  the  axis 
to  make  anchorage  upon ;  and  the  highest  points  are  not  in  the 
axial  lines,  because  if  the  centre  of  the  Bridge  was  made  to  coin- 
cide with  the  summit,  the  axis  would  be  thrown  too  far  down 
the  hill-side  of  the  Dunderberg,  or  too  high  on  the  edge  of  the 
mountain  on  the  east  side  of  the  river. 

As  before  stated,  westwardly  of  Round  Island  there  is  a  marsh, 
connecting  it  with  the  right  bank  of  the  river.  This  marsh  is 
deep,  and  soft ;  but  the  extent  of  the  mud  has  not  been  ascer- 
tained by  us.  From  various  indications,  my  assistants  report 
their  belief  that  it  is  from  forty  to  fifty  feet  deep. 

The  marsh  is  1937  feet  wide  between  the  rocks  on  either  side. 

If  two  spans  of  a  Suspension  Bridge  or  any  analagous  system 
were  built  at  this  crossing,  they  must  be,  if  equal  in  extent,  each 
two  thousand  feet  in  the  clear.  It  is  possible  however  that  spans 
of  unequal  length  might  be  made  at  this  place,  one  of  which 
would  be  of  less  extent. 

In  any  case,  very  heavy  masonry  in  the  approaches  and 
abutments,  would  be  required. 


9 


The  straint)  upun  the  muiii  cables,  ut  the  above  named  section 
hove  been  calculated,  and  you  will  find  their  ratio  tabulated 
with  those  obtained  at  the  other  crossings.  '         • , 

A  design  has  been  made,  and  some  estimates  worked  up  for 
one  span  over  the  water  way  of  the  river,  and  masonry  arches 
over  the  marsh,  and  the  easterly  approach  ;  and  as  regards  its 
architectural  effect  may  be  very  acceptable  ;  but  before  any  deci- 
sion could  be  properly  made  for,  or  against  it,  many  other  local- 
ities should  be  examined,  and  you  may  find  it  suffers  by  compar- 
ison with  them. 

You  will  find  in  the  table  of  ratios  an  approximation  to  the 
quantity  of  rupturing  force,  relatively  exerted  at  this  point,  and 
others,  and  also  an  approximation  to  the  quantity  of  masonry, 
and  work  to  be  done  on  the  approaches.  , 

The  A.  A',  line  is  the  most  southerly  crossing  investigated  in 
detail.  Below  this  the  river  is  so  mucli  wider  and  the  circum- 
stances generally  so  much  less  favorable  than  those  further  up 
stream,  that  nothing  in  the  way  of  measurements  were  made 
under  my  direction.  The  United  States  Coast  Survey  however 
accurately  present  the  shore  lines,  and  they  have  been  transfer- 
red to  the  accompanying  map.  The  connections  by  rail  with 
the  A.  A',  line  are  spoken  of  elsewhere. 

The  next  line  in  order  of  progression  up  the  river,  is  marked 
B.B'. 

Between  A.  A',  and  B.  B'.,  the  Kiver  banks  were  run  out  by 
transit  and  the  shore  lines  of  the  marsh  and  of  Ionia  Island, 
traced  by  compass  and  chain  at  the  time  the  examinations  were 
made  last  winter,  for  the  information  of  the  Legislature ;  some 
of  the  measurements  were  made  on  the  ice,  but  the  greater  part 
of  the  work  was  connected  by  triangulations,  from  bases,  care- 
fully measured  on  the  track  of  the  Htidson  River  Kail-road, 
which  afforded  excellent  facilities  for  extreme  accuracy.  It  is 
from  these  measures  that  this  portion  of  the  map  is  made  up. 

I  find  that  it  corresponds  very  nearly  with  the  work  of  the 
United  States  Coast  Survey,  except  in  the  position  of  the  shore 
line  of  Ionia,  which  represents  the  river  to  be  wider  in  some 
places,  and  narrower  in  others,  by  a  few  feet,  then  we  make  it. 


10 


I  am  particular,  to  call  your  attention  to  this  discrepancy  as 
the  matter  may  be  referred  to  in  future,  on  account  of  the  veiy 
high  authority  usually  accredited  to  government  work.  But  as 
our  work  was  very  carefully  done,  and  under  very  favorable  cir- 
cumstances and  proved  its  own  accuracy  by  correctly  closing 
upon  our  own  bases  I  have  assumed  its  reliability  in  the  cal- 
culations, using  our  own  data,  and  I  think  this  may  fairly  be 
done,  when  the  discrepancy  is  but  little  and  where  our  work 
was  special,  and  theirs  only  general;  but  it  is  of  too  much  im- 
portance not  to  call  your  attention  to  the  fact. 

The  section  on  B.  B'.  was  never  completed.  Such  examina- 
tions as  were  made,  showed  an  unfavorable  result  when  compar- 
ed with  other  lines  and  as  these  conclusions  are  easily  arrived 
at  on  the  ground,  without  much  analysis,  it  was  deemed  unwise 
to  expend  time,  and  money  to  no  purpose. 

The  very  favorable  manner  in  which  this  location  B.  B'.  can 
be  approached  from  the  y^estward  by  any  line  of  railway  induced 
me  at  first  to  consider  it  quite  important,  more  particularly  as  a 
perpendicular  crossing  of  the  water-way  of  the  river,  from  the 
shores  of  Ionia  near  this  section,  showed  less  distance  then  at  any 
other  place  for  many  miles.  In  the  table  of  comparisons,  the 
value  mathematically  of  this  line  is  represented  therefore  only 
approximately,  which  must  be  borne  in  mind. 

From  the  upper  end  of  Ionia  Island  to  Fort  Clinton,  and  St. 
Anthony's  Nose,  our  work  corresponds  very  nearly  with  the 
coast  survey.  Our  system  of  triangulations,  and  measurements, 
here  were  the  same  as  below,  which  is  an  additional  reason  for 
presuming  their  accuracy,  and  they  were  proved  again  by  careful 
chaining  on  the  ice  across  the  river  at  Fort  Clinton. 

From  Fort  Clinton  to  St.  Anthony's  Nose,  we  have  several 
lines,  varying  in  position  from  one  another  a  few  feet. 

The  section  of  calculation,  and  estimate  is  at  C.  C.  and  this  is 
the  unit  of  comparison  with  all  the  other  crossings. 

Here  plans  have  been  made  for  a  Bridge  to  carry  broad,  and 
narrow  guage  tracks  for  railway  travel,  and  wagon  roads,  and 
foot  passages. 

Three  BjBtemd  of  parapets  have  been  considered,  and  all  the 


11 


IS 


parts  of  the  roadways,  cables,  anchorage,  wind-guys,  tmsses, 
towers,  foundations,  anchor-pits,  drains,  tunnels  and  other  parts 
drawn  to  a  scale,  and  the  resistance,  strain,  compression  and  all 
other  forces,  together  with  the  weights  of  the  parts  in  equilibrium, 
suspended  and  on  foundations,  calculated  and  the  cost  estimat- 
ed and  tabulated. 

Here  the  Bridge  would  have  the  following  general  dimensions. 

Clear  span,  1600  feet. 

Distance  between  centres  of  towers,  1665  feet. 

Total  length  of  Bridge,  including  the  anchors,  2499  feet. 

Height  of  Bridge  above  the  water  155  feet. 

These  dimensions  now  constitute  a  theoretical  Basis  of  Com- 
parison,  between  this  line  and  all  other  locations.  This  however 
does  not  necessarily  express  any  preference  for  the  location,  or 
otherwise,  it  is  merely  the  method  employed  of  making  com- 
parisons easily. 

"Next  in  order  is  the  Fort  Montgomery  section,  to  St. 
Anthony's  Nose.  This  line  is  marked  D.  D'.  and  here  the 
span  would  be,  as  nearly  as  can  be  ascertained  without  making 
working  drawings,  sixteen  hundred  and  fifty  (1650)  feet  in  the 
clear.  This  locality  possesses  a  very  great  advantage  of  ap. 
proaching  the  mountain  on  the  east  side  of  tho  river  from  the 
west  side  in  the  most  favorable  direction :  far  better  than  that 
from  Fort  Clinton. 

The  west  bank,  however,  is  comparatively  low  here,  and  the 
approaches  would  be  long,  and  the  masonry  heavy :  you  will  see 
by  the  table  of  the  comparisons,  how  this  difficulty  is  oftset  by 
the  saving  of  excavation  on  the  hill-side  opposite. 

Very  many  persons  whose  judgement  is  worthy  of  respect, 
consider  this  location  far  more  desirable  than  the  C.  C.  line. 

The  approaches  to  all  the  sites  being  considered  separately, 
but  as  a  part  of  the  who7.e  problem,  we  pass  on  to  the  Section 
at  the  Consute  Island. 

It  may  be  well  to  remark  that  at  Fort  Montgomery,  a  chain 
to  obstruct  the  passage  of  the  British  fleet,  was  stretched  out  on 
a  line  very  nearly  corresponding  to  our  vertical  section  on  the 
line  D.  D'.  and  arguments  are  framed  upon  thi'i  fact,  calculated 
to  misslead  those  who  do  not  thoroughly  investigate. 


12 


It  is  claimed  that  the  American  general  under  the  advice  of 
the  most  able  engineers  of  the  time,  selected  this  place  for  the 
obstruction  of  the  river,  bec.iuse  it  is  narrower  than  elsewhere 
and  afforded  the  best  anchorage  for  the  chain. 

The  fact  that  the  chain  was  put  there,  after  oareful  considera- 
tion is  not  doubted,  and  that  it  was  a  very  great  acheivement 
for  the  times  and  circumstances  under  which  it  was  done  is 
readily  admitted,  but  that  the  crossing  is  narrower  here  than 
elsewhere,  is  denied,  not  only  docs  the  United  States  Coast 
Survey,  represent  it  more  than  two  hundred  feet  wider  than 
elsewhere,  but  our  own  triangulatioiis  and  measurements,  made 
on  the  ice  last  winter  correspond. 

Why,  then,  was  the  chain  i)ut  here?  we  are  asked.  It  was  for 
these,  among  other  reasons,  that  Forts  Clinton,  and  Montgom- 
ery held  the  river  from  favorable  positions,  and  were  already 
built,  that  by  placing  the  chain,  where  it  was  put,  Fort  C'linton 
could  take  the  enemy  in  front  at  long  ranges  and  in  flank  as 
they  approached;  and  that  Fort  Montgomery  could  take  them  in 
flank,  with  their  best  guns,  whereas  if  the  west  end  of  the  chain 
had  been  swung  to  Pell's  Point,  Fort  Montgomery  would  have 
reached  the  enemy  from  an  oblique  froi  J,  only  at  the  chain,  or  at 
long  range  as  they  approached  it.  If  the  chain  had  been  put  at 
Icnia  or  at  Consute  where  the  rivc'  is  much  ntirrower,  the 
two  forts  would  have  borne  upon  the  enemy  in  the  first  case  at 
long  range  only  in  front,  without  the  advantage  of  a  flank  fire, 
and  in  the  other  case  ai  still  longer  range  in  the  rear  only. 

If  we  push  the  inquiry  further  and  ask  why  were  not  the 
forts,  built  at  points,  where  the  river  could  be  chained  to  the 
best  advantage,  I  answer  that  the  r'v:'r  was  chained  to  the  best 
advantage  in  a  military  point  of  view ;  the  chain  was  an  after 
thought,  the  forts  had  been  built  in  tlie  best  position  to  com- 
mand the  river  and  the  chain  was  put  where  the  forts  could 
best  protc  ot  it. 

There  ^  no  relation  between  the  considerations  that  govern 
the  construction  of  inilitary  offensive  and  defensive  works,  and 
such  a  structure  for  purely  conimercMal  i)urposes  as  you  contem- 
plate erecting,  because,  the  place  was  more  suitable  for  a  fort, 


13 


and  chevaux  de  frieze,  it  does  not  necessarily  follow  that  it  is 
best  for  a  bridge. 

The  lines,  and  sections  E.  E'.  at  Consule  or  Marsh 
Island,  next  require  attention. 

From  a  point  some  three  quarters  of  a  nuie  above  Fort 
Montgomery  to  the  marsh,  south  and  west  of  the  Consute 
Island  I  have  depended  altogether  on  the  U.  S.  Coast  Survey, 
for  the  shore  line  of  the  river.  The  upper  contours,  for  topogra- 
phy were  made  under  my  directions. 

At  ihe  marsh,  aiid  Consute  we  have  our  own  work  again, 
to  rely  upon,  and  find  it  corresponds  very  nearly  with  the 
Coast  Survey;  we  have  however  taken  all  the  drtails,  they  have 
only  the  general  ficts. 

The  width  of  the  river  at  the  narrowest  place  is  fourteen 
hundred  and  sixty -five  feet,  and  a  bridge  may  be  made,  having 
a  clear  span  of  fourteen  hundred  and  eighty  feet,  and  total  cen- 
tral span  between  centres  of  towers  of  about  fifteen  hundred 
and  ten  feet. 

This  is  wiih  one  exception,  the  narrowest  place  on  the  river 
within  your  assigned  limits,  and  in  fact  within  a  range  of  one 
hundred  miles  or  more,  and  that  other  place  is  at  the  north  end 
of  Grants  Island,  where  the  river  may  be  some  thirty  [30] 
feet  less  in  width,  upon  a  point  of  rocks,  utterly  unsuited  for  our 
use  on  the  westerly  side,  an^^  on  the  east,  the  rocks  are  so  steep 
and  directly  perpendicular  to  the  axis,  that  without  the  expen- 
diture of  incredible  sums  of  money,  the  crossing  would  be  im- 
practicable ;  besides,  if  this  narrow  Grants  Island  passage  is 
used,  it  would  require  about  two  tliousand  feet  of  trestle  work, 
one  hundred  and  fifty-five  feet  high  to  approach  it  from  the  west. 

The  line  E.  E'.  affords  good  facilities  for  anchorage  on  the 
east  side  at  little  expense,  on  the  west  they  will  be  equally 
good,  and  safe,  but  will  cost  some  more,  and  there  is  abundance 
of  room  on  either  side  of  the  river,  for  all  the  approaches  by  rail, 
and  highway. 

The  greatest  draw-back  to  this  crossing  is  the  cost  of  the  ap- 
proach between  the  backstays  on  the  westerly  side. 

Above    Consute  Island   to    Buttermilk   Falls  I  have  again 


14 


relied  upon  the  U.  S.  Coast  Survey  for  the  shore  lines  represen* 
ted  on  the  map. 

Tiiere  is  no  desirable  section  upon  which  to  cross  within  the 
distance ;  at  least  there  are  so  many  other  places,  so  much  more 
favorable  elsewhere,  that  no  effort  has  been  made  to  do  anything 
with  what  opportunities  may  be  here  presented. 

It  is  proper  to  say  though,  that  there  are  those  who  warmly  ad- 
vocate, a  crossing  near  Cozsen's  directly  at  the  Falls ;  but  in 
my  opinion  it  is  not  worthy  of  consideration,  where  so  many 
much  more  favorable  points  are  to  be  found. 

You,  thus,  have  all  there  is  within  your  assigned  limits   au- 
thorized by  law,  and  the   decision  will   in   all  probability  be 
arrived  at,  in  favor  of  one  of  the  five  sections  indicated,  or  upon 
"  some  slight  modification  of  one  of  them. 

You  !  !  ee  by  the  table  of  comparisons  of  strain  that  there 
is  great  disparity  between  the  forces  exerted  at  the  different  pla- 
ces. 

The  A.  A',  line  at  Round  Island  shows  the  greatest  strain 
upon  the  main  cables,  and  by  far  the  greatest  quantity  of  ma- 
sonry, and  in  fact  the  greatest  of  everything  involving  cost, 
while  the  facilities  of  bringing  a  rail-road  line  to  it  and  from  it, 
are  equal  to,  if  not  superior  to  any  other  place,  but  there  is  no 
room  on  either  side  for  anything  like  a  town,  or  in  fact,  even 
depots  or  sidings  without  immense  expenditures,  as  the  lines 
are  on  the  steep  rocky  side  hills . 

The  line  E2  shows  the  manner  of  approaching  the  A.  A'  loca- 
tion from  the  west  with  a  grade  of  sixty  feet  to  the  mile,  and  the 
line  E3  shows  the  connection  with  the  Erie  and  New  England 
Bailway,  and  the  Hudson  River  Railroad  on  the  easterly  side. 

At  the  point  F  about  one  half  a  mile  from  the  dump  of  the 
Forest  of  Dean  Iron  mine  Railway,  near  the  house  of  Mr.  Noah 
Brooks,  there  is  the  bottom  of  a  natural  pass  in  the  hills,  five 
hundred  and  twenty  feet  above  tide,  which  is  common  to  all 
lines,  coming  from  the  west  to  any  site  you  may  select  for  the 
crossing  of  the  Hudson  River.  I  wish  to  impress  this  fact 
distinctly  upon  your  minds  as  very  much  depends  upon  it. 

Now,  to  reach  the  A.  A',  line  from  this  place  F.  with  a  grade 


15 

of  sixty  feet  to  the  mile,  you  must  not  only  use  all  the  distance 
there  is  directly  on  the  side  hill,  but  the  line  must  be  elongated 
by  developement  to  F'.  and  back  again  to  F".  and  thence  to  the 
point  A.  this  will  bring  the  train  in  the  right  direction  to  cross 
the  bridge  with  the  engine  in  front :  otherwise  if  a  line  were 
taken  from  F.  to  A.  on  the  side  hill,  the  grade  would  be,  one 
hundred  feet  to  the  mile. 

Returning  again  to  the  common  point,  F.  to  reach  the  C.  C. 
section,  or  any  of  the  sections  from  Fort  Clinton  to  St.  Antho- 
ny's nose,  we  must  develope  the  railway  location  to  the  westward 
of  Highland  lake,  to  F'.  and  return  to  C. 

This  will  bring  the  train  coming  from  the  west,  so  that  the 
locomotive  will  be  at  the  rear,  when  it  reaches  tlie  bridge . 

There  are  some  advantages  in  this  plan  of  cro8sing,as  a  special 
engine  may  be  used  by  the  Bridge  Company,  for  taking  all 
trains  across,  that  come  from  any  direction  ;  this  would  pre- 
clude the  possibility  of  any  collision  upon  the  bridge,  and  has 
other  advantages,  such,  as  the  care  that  would  be  taken  by 
the  engine  driver,  to  run  according  to  rules  established  by  the 
Bridge  Company,  while  if  all  Companies  are  allowed  to  take 
their  own  trains  across  in  their  own  way,  with  their  own  engines 
and  men,  such  rules  cannot  be  so  easily  enforced. 

Or,  if  it  is  thought  best,  a  turn  may  be  made  at  H.  which  will, 
not  augment  the  development,  and  will  place  the  trains  head  on, 
to  cross  the  Bridge  in  the  usual  way. 

On  the  easterly  side  of  the  river,  the  connections  with  rail- 
roads to  the  south  and  east  from  the  C.  V.  line,  must  be  made 
by  a  very  heavy,  and  expensive  cut  in  St.  Anthony'  Nose.  If 
a  directly  descending  grade  from  F.  to  Fort  Clinton,  is  run  by 
the  shortest  route  F.  C.  it  will  be  one  hundred  and  ninety  feet 
to  the  mile. 

The  connections  to  the  north  and  east,  are  more  readily  made, 
but  either  a  reverse  V.  must  be  adopted,  or  a  tunnel  on  a  curve 
to  make  the  best  combination  practicable  for  leaving  the  bridge 
in  both  directions. 

We  must  again  return  to  the  paint  F.  and  follow  the  line  to 
F'.  F".  there  return  to  D.  to  reach  the  D.  D'.  line. 


I 


16 


You  will  readily  see  the  facility  with  which  this  Fort  Mont- 
gomery and  St.  Anthony's  Nose  line  leaves  tlic  side  hill,  on 
the  east  going  to  the  south. 

Those  of  you,  who  have  seen  the  ground  cannot  fail  to  appre- 
ciate the  importance  of  this  fact. 

The  very  great  saving  there  is  in  the  lines  of  approach  on  the 
east,  on  the  C.  C.  line,  is  too  obvious  to  be  overlooked,  but  we 
must  not  forget  that  to  reach  the  connections  of  the  Boston, 
Hartford,  and  Erie  Railway  near  Fishkill  if  such  a  road  is  ever 
built,  or  to  get  to  the  Dutchess  and  Columbia  Kail-road  now 
being  constructed,  we  must  turn  to  the  nortli. 

This  is  not  such  an  easv  matter  to  do ;  in  fact  the  work  will 
be  exceedingly  heavy,  and  seems  to  be  almost  or  quite  impracti- 
cable, unless  we  continue  the  direction  of  movement  after 
crossing  the  Bridge  from  the  west,  to  the  point  I  tliere  put  in  a 
V,  and  reverse  to  the  north  on  the  lin';  K :  tliis  will  bring  you 
into  a  tunnel  at  J.  K.  or  a  deep  cut  in  the  rock  costing  as 
much  or  more  than  an  under-ground  route. 

From  F.  to  D.  by  the  most  direct  route  the  grade  will  be  one 
hundred  and  ninety  feet  to  the  mile,  hence  tlie  necesJty  for 
making  the  development  to  F'.  if  you  require  the  gradients  not 
to  exceed  sixty  feet  to  the  mile. 

The  line  F.  L.  L'.  L".  saves  developing  so  far  to  the  south  as 
the  Point  F'.  and  this  modification  is  applicable  to  the  locations 
of  the  A.  A':  B.  B':  C.  C:  and  D.  D'.  sections. 

We  will  now  for  the  fifth  time  return  to  the  point  F.  and 
carry  your  eye  along  the  blue  line  M.  M'.  M".  M'".  to  E. 

This  shows  the  westerly  a])pro;ich  to  tlie  crossing  at  the 
section  E.  E'.  at  Consute  Is-land,  including  liie  necessary 
development,  to  obtain  a  grade  of  sixty  feet  to  the  mile.  From 
F.  to  E.  by  the  most  direct  line,  the  grade  is  ninety-one  feet 
to  the  mile  along  the  undevelo])ed  line  F,  N,  N',  N",  E. 

And  now,  allow  me  to  make  a  statement  that  you  doubtless 
may  have  anticipated.  The  developed  lines  of  sixty  feet  grade 
to  the  mile  from  F.  to  A.,  F.  to  B.,  F.  to  C,  F.  to  D.,  F.  to  E. 
are  exuctly  the  same  length  in  feet  and  inches. 

It,  therefore  follows,  that  as  the  point  F.  is  on  the  location 


17 


from  Turner's  to  the  Hudson  River,  and  is  common  to  iJl  the 
Bridge  locations,  that  »vlth  sixty  feet  grades,  developed  lineSy 
all  the  proposed  Bridge  Crossings  are  precisely  the  same  distance 
from  the  Erie  Railway,  when  they  are  made  at  an  elevation  of 
one  hundred  and  fifty-five  feet  above  tide,  while  if  we  follow  the 
direct,  and  shortest  route  to  the  river,  the  most  favorable  grades 
upon  an  undeveloped  line  would  take  us  to  the  E.  E'.  or  Oonsute 
Island  location. 

The  next  best,  so  far  as  grades  for  rail-road  approaches  go, 
would  be  at  the  A.  A',  line  at  Round  Island.  The  next  best  is 
the  B.  B'.  section  at  the  upper  end  of  Ionia. 

The  two  least  favorable  in  this  respect  and  which  if  you  have 
been  enabled  to  keep  your  mind  on  this  dry,  but  necessary  sub- 
ject, you  will  find  to  be  at  the  C.  C:  and  D.  D'.  sections  respec- 
tively at  Forts  Clinton  and  Montgomery,  and  so  far  as  undevel- 
oped lines  afiTect  the  question  of  grades,  they  are  alike  and  the 
worst  there  are. 

At  the  general  location  at  Consute  Island  the  details  on 
three  sections  have  been  worked  up,  one  of  these  lines  for  pur- 
poses hereafter  referred  to,  has  been  put  at  a  higher  elevation 
above  tide. 

The  other  is  merely  a  modification  of  the  E.  E'.  line  to  ascertain 
the  beat  way  of  making  the  easterly  towers. 

The  modified  high  line  at  this  section  is  for  the  purpose  of 
facilitating  anchorage  on  the  west  side,  this  line  is  0.  0'. 

The  examinations  that  have  been  thus  far  made  on  the  ground, 
on  this  high  line  are  not  sufficient  in  detail  to  justify  any  con- 
clusions, but  if  it  is  found  best  to  adopt  them,  it  will  reduce  the 
grades  on  the  undeveloped  line  to  eighty-eight  feet  to  the  mile, 
and  shorten  the  length  of  the  developed  sixty  feet  to  the  mile 
line,  thirteen  hundred  and  twenty  feet.  So  that  with  the  modi- 
fied crossing,  the  E.  E'.  section,  would  be  a  quarter  of  a  mile 
nearer  to  Turner's,  on  the  Erie  R.  R.  than  any  other  location : 
Now,  I  think,  you  will  readily  see  :is  I  see,  by  calculations,  and 
on  the  ground  that  "  the  sura  of  the  whole  matter"  resolves  it- 
self into  a  comparison  between  the  C.  C.  line,  and  the  E.  E'.  line, 
as  all  the  others  have  features  well  defined  against  them,  which 
are  not  so  prominent  against  these  two. 


18 


Your  charter  contemplates  the  construction  of  a  Bridge  for 
the  passage  of  railway  trains  as  well  as  the  travel  of  common 
highways;  whether  you  can  dispense  with  one,  or  the  other,  is  a 
question  for  lawyers,  or  the  courts  to  decide.  I  have  supposed 
you  are  required  to  make  the  means  for  the  jtublic  to  cross  in 
their  own  way  with  their  teams,  horses,  cattle,  and  other  prop- 
erty, if  you  make  the  liridge  at  ail,  in  tliis  I  may  be  mistaken, 
and  there  are  very  intelligent  gentlemen,  who  hold  another 
opinion,  namely,  that  you  can  make  the  railroad  Bridge,  Avith- 
out  providing  for  any  other  kind  of  travel. 

Ifthis  is  the  correct  view  of  the  c:iHe,tlK!n  you  >iliould  surely 
consider  it  with  reference  to  the  kind  of  travel,  you  propose  at 
the  different  localities.  Supposing  that  you  have  the  right  to 
do  as  yon  please  in  this  respect,  you  wcuild  save  very  greatly 
by  not  making  a  highway  bridge,  if  you  adopt  the  C.  C.  line. 
At  this  section  there  are  no  public  roads  that  come  near  the 
place,  and  to  construct  one  along  the  face  of  the  cliifs,  south  of 
St.  Anthony's  Nose,  towards  Peekskill,  and  to  prepare  a  place 
for  the  connection  of  any  Rail-road  leading  to  the  north  from 
the  Bridge  is  very  expensive. 

In  fact,  over  400,000  cubic  yarth  of  rock  must  be  removed  for 
this  purpose,  collectively,  including  what  is  necessary  to  make 
room  for  the  anchorage. 

It  may  be  that  the  present  route  from  Peekskill  to  Garrisons, 
can  be  tapped  after  it  crosses  the  mountain,  and  in  this  way 
turn  to  the  south  from  the  old  Demiui;  Estate  along  the  fs\ce 
of  the  hill. 

This  would  perhaps  save  one  hundred  thousand  dollars  ($100- 
000.) 

On  the  west  side  of  the  river,  the  cost  would  be  much  less,  as 
merely  an  ordinary  road,  for  say  a  mile,  or  less,  would  be  re- 
quired, with  a  Bridge  over  Popolopen  Creek. 

The  great  travelled  road  from  the  East,  to  the  West,  through 
this  part  of  the  country  is  from  Lake  Mahopae,  to  ^7est  Point 
via  Garrison's. 

At  the  Consute  Island  the  Bridge,  would  be  directly  in  the 
line  of  this  travel,  requiring  not  more  than  a  quarter  of  a  mile 


19 


IS  a 


way 
face 


1  the 
nile 


of  highway  to  be  built  altogether,  to  give  all  the  'facilities  that 
could  be  required  on  both  sides  of  the  river. 

Then  again,  at  Consuto  Island,  the  anchorage  on  the  west 
side  will  be  more  complieate«l,  and  costly  then  at  Fort  Clinton, 
exactly  how  much  this  will  be,  at  either  place  cannot  be  known, 
until  the  rocks  are  uncovered,  and  tested. 

There  is  an  important  feature  at  Consute  not  to  be  over, 
looked.  The  wide  plains  on  either  side  afford  the  means  of 
making  all  the  depots,  cattle  yards,  coal  storage  grounds,  and 
every  other  facility  of  dc  kind,  while  at  the  C.  C  line,  these 
facilities  exist  only  at  the  Fort  Clinton  side. 

The  cost  of  the  right  of  way  at  either  of  these  two  places, 
will  be  considerable  if  reckoned  by  the  values,  the  owners,  now 
put  upon  their  lands,  but  as  this  is  a  question  for  a  jury,  if  needs 
be,  I  have  not  investigated  it  very  thoroughly.  It  will  be,  or  I 
think  it  should  be  very  nearly  as  much  at  one  place  as  at  the 
other . 

So  far  as  the  interests  of  the  Erie  and  New  England  R.  B. 
Company,  may  enter  into  your  calculations,  it  would  be  best 
for  them  to  have  the  bridge  at  "  Fort  Clinton"  because  it  will 
cost  less  for  them  to  reach  the  Bridge  than  at  Marsh  Island.  If 
however,  you  consider  also  a  branch  line  to  Fishkill,  which  cer- 
tainly should  come  into  the  case,  the  railroads  collectively,  will 
not  cost  more  from  one  site  than  from  another. 

The  topography  of  the  country  is  such,  that  whatever  applies  • 
to  the  branch  line  from  Fishkill,  applies  equally  to  the  Dutchess 
and  Columbia  liailroad,  or  to  the  Boston,  Hartford,  and  Erie,  if 
it  terminates  at  Fishkill.  Tiie  wind  comino;  from  the  north-west 
is  recorded  as  the  most  severe  tliat  blows  in  this  region.  With 
reference  to  it,  Consute  Island  is  the  best,  for  the  Bridge  will 
not  be  the  only  object  in  a  concentrated  focus. 

At  Fort  Clinton,  the  Bridge  woulu  be,  as  it  were,  at  the  neck 
of  a  funnel.  If  you  turn  your  thoughts  for  a  moment  to  the 
topography  of  the  Country,  this  fact  will  be  apparent. 

If  you  build  it  at  the  Marsh  Island  this  difficulty  will  bo 
avoided.  The  plain  is  wider  here  than  elsewhere,  although  the 
river  is  narrower,  aud  the  wind  will  not  be  concentrated  so  much 


20 


il'i 


,  I 


upon  it.  I  do  not  consirler  this,  Ijowever,  an  more  than  an  inci- 
dental advantage  in  favor  oi"  the  upper  line,  tor  ample  provision 
can  be  made  at  either  place  for  security  against   any  wind. 

So  far  I  hare  not  attempted  in  the  question  of  location  to  in- 
volve the  subject  of  any  special  form  of  structure,  altljough  it 
must  be  manifest  to  you,  that  there  should  be  changes  of  im- 
portance, due  to  the  place,  and  the  kind  of  travol,  paiiioularly 
that  advantage  be  taken  of  any  favorable  circumstances  of 
ground,  that  each  site  may  present.  Some  general  facts,  and 
considerations  may  be  useful  in  refreshing  your  memories  upon 
points,  I  have  already  had  the  honor  to  lay  before  the  associa- 
tion, from  which  your  Company  sprang. 

These  are  added  to  and  raoditied  in  view  of  the  more  complete 
information,  we  now  have  on  tlie  subject,  and  the  greater  amount 
of  details  that  have  been  collected. 


OF    THE   SUSPENSION    BRIDGE. 

At  first,  it  might  appear  to  l)e  almost  impracticable  to  make 
80  considei'able  a  span,  as  that  which  is  required  to  cross  the 
Hudson  River,  at  any  point  without  the  assistance  ot'intermedi- 
ate  piers  of  any  kind.  But  the  experience  of  tlie  world,  has 
shown  that  the  limit  that  can  practi(!:illy  be  attained  is  not  even 
approached  in  your  case. 

It  is  true  that  the  span  required  is  greater  than  that  of  any 
railroad  bridge  yet  constructed  of  one  single  opening,  but  never, 
theless  so  certain  are  the  data  upon  which  the  calculation  of  the 
strength  of,  and  strain  upon  all  the  points  is  made,  that  we  can 
with  perfect  exactness,  and  accuracy  determine  the  conditions, 
that  will  govern  the  passage  of  every  load  upon  the  structure. 

Let  us  look  at  a  few  of  the  si!nj)le  eienientary  principles,  that 
are  involved. 

In  the  position  of  the  cable  of  the  Suspension  Bridge,  the 
forces  which  tend  to  rupture  it,  are  increased  by  the  manner  in 
which  they  act  upon  the  curves. 

Practically  they  are  nearly  <louble  that  which  they  would  be, 
if  they  were  sustained  by  the  wire  endwise. 


31 


any 
ever, 
the 
can 
;ion8, 
re. 
that 


be, 


If  therefore  a  strand  of  wire,  which  would  carry  fifteen  hun- 
dred pounds,  less  its  own  weijiht,  say  fourteen  hundred,  is 
strained  when  put  into  the  position  of  the  cable,  with  double  its 
weight  in  consequence  of  the  shape  of  the  curve,  it  follows  that 
there  would  be  something  over  five  hundred  and  fifty  pounds, 
left  for  the  strand  to  carry,  besides  its  own  weight. 

Then,  if  in  order  to  be  perfectly  safe,  we  say  that  the  strand 
shall  only  carry  one  fifth  (})  of  what  will  break  it,  it  follows 
that  the  wire  will  carry  its  own  weight,  and  something  over  one 
hundred  pounds  besides,  when  it  is  in  place  in  the  cable.  A 
very  simple  calculation  determines  how  many  strands  are  neces. 
sary  to  carry  any  given  load  ;  for  if  one  strand  in  position  will 
carry  its  own  weight,  and  one  hundred  pounds,  two  strands  will 
carry  their  owa  weight,  and  two  hundred  pounds,  and  -lo  inde- 
finitely, and  we  have  merely  to  ascertain,  what  load  can  at  any 
time  come  upon  the  Bridge,  to  determine  the  exact  number  of 
strands,  that  are  necessary  to  carry  with  perfect  safety,  the  very 
heaviest  load. 

If,  however,  on  the  other  hand  the  span  of  the  bridge  k  so 
great,  that  the  wire  will  not  sustain  its  own  weight,  for  the 
necessary  length,  it  becojues  impracticable  with  our  present 
materials  to  make  the  bridge  of  such  a  span. 

In  your  case,  the  span  required  to  cyohh  the  bridge,  at  any  of 
the  points  within  the  Highlands,  will  not  exceed  one  hali  of  that 
which  would  be  safe. 

I  shall  not  attempt  to  enter  upon  the  discussion  analytically 
of  those  questions,  which  involve  the  ultimate  destruction  of  a 
work  of  this  kind  in   equilibrium. 

For  your  purpose  now  it  will  be  sufficient  to  say,  that  in  Eng- 
land, in  France,  in  Germany,  in  Peru,  and  in  China,  these  bridges 
have  been  in  use  for  many,  many  years. 

In  all  the  calculations  of  the  strength  and  strain  of  the  Bridge, 
we  have  allowed  for  five  times  as  much  weight,  as  can  be 
brought  upon  it,  under  any  circumstances. 

A  train  of  locomotives  of  the  heaviest  kind,  filling  the  bridge 
from  one  end  to  the  other,  and  rushing  over  it  at  the  rate  of 
thirty  miles  to  the  hour,  while  the  road-way  is  filled   with  a 


pi 


(i! 


I 


crowd  of  people,  as  close  as  they  can  stand,  which  is  the  heaviest 
possible  load,  that  can  be  brought  under  ordinary  circumstances 
upon  ft  common  highway,  would  not  strain  the  Bridge  more 
than  one  sixth  (1-0)  of  that  which  it  is  able  to  bear. 

On  either  side  of  the  llivcr,  the  best  possible  advantages  exist 
for  anchorage  in  the  granite  rocks. — They  are  better  however 
as  before  stated  in  some  positions  than  in  others. 

The  anchors  are  made  in  such  a  manner  that  not  only  all  the 
force  exerted  upon  them,  is  insutlicient  to  rupture  the  rocks, 
but  if  a  cone  of  stones  of  the  si/.e  of  the  cone  of  rupture,  was 
simply  to  be  laid  upon  the  anciioruge,  it  would  be  enough  to 
hold  them  in  place. 

That  is  to  say,  if  the  stones  were  simply  piled  up,  instead  of 
being  natural  rocks,  in  their  original  bed,  their  weight  would 
be  sufficient. 

We,  therefore,  do  not  de[)end,  for  the  stability  of  the  struc- 
ture upon  the  cohesion  of  the  rocks  themselves.  This  is  a  sup- 
plementary and  additional  advantage  and  could  be  dispensed, 
with,  but  in  order  to  use  every  precaution,  I  have  provided  that 
all  the  interstices  of  the  rocks,  should  be  picked  out  clean,  and 
where  the  seams  are  considerable,  they  are  to  be  filled  with 
hydraulic  cement  concrete  ;  where  they  are  less,  lead  will  be  used, 
and  where  they  are  small,  melted  sulphur  is  to  be  poured  in. 

Thus  not  only  the  moisture  will  be  kept  out,  which  might 
otherwise  corrode  the  anchors,  and  anchor  chains,  but  the  whole 
surrounding  rock,  will  be  made  into  a  homogeneous  mass.  The 
anchor  pits  are  also  to  be  drained  by  tunnels  below. 

The  main-stays,  the  cables,  the  guys,  and  the  roadways,  are  at 
any  temperature  either  the  hottest  weather  of  summer,  or  the 
coldest  weather  of  winter,  in  perfect  equilibrium,  and  the  stabil- 
ity of  the  structure  will  depend  not  upon  any  truss,  or  upon  any 
counter-brace  or  guys,  but  its  owji  dead  weight  will  keep  it  in 
place. 

The  object  in  making  the  bridge  in  tliis  mauner,  is  to  prevent 
the  possibility  of  any  strain  coming  unduly  upon  any  of  the 
parts. 

Where  the  whole  Structure  is  in  perfect  equilibrium,  nothing 
could  be  strained  beyond  its  proper  proportion. 


S3 


ight 


rent 
the 

ling 


IfatruHH  HhouM  hv  used  in  foniu'ction  with  the  cablt»H,  the 
ends  of  which  are  inserted  in  the  solid  rocks,  the  trusH  hning  in 
a  straight  line,  while  the  cables  were  u|Min  the  curve,  it  neces- 
«jirilv  follows,  that  where  the  truss  and  cables  uro  connected 
together,  Avhere  changes  of  tetuperalure  such  as  are  usual  in  our 
climate  take  place,  the  truss  will  alternately  have  tlie  whole 
weight  to  carry,  and  then  notiiiiig  at  all,  while  the  cables  on  the 
otlier  i>and  will  alternately  have  the  whole  weight  to  carry,  and 
then  nothing  at  all. 

In  so  large  a  Structtu'e  as  this,  it  is  necessary  that  each  part 
should  bear  its  own  proportion  of  the  load  ;  heiure  tlie  cables 
are  made  to  carry  the  weight  of  the  deck  of  the  bridge,  and 
any  load  upon  it,  and  their  own  weight,  and  the  parapets  are 
merely  used  to  distribute  the  load,  alotiir  the  cables. 

Experience  has  shown  that  trusses,  however  desirable,  they 
may  be,  when  they  are  i\ot  connected  with  the  catenary,  are 
very  ineffectual  when  they  become  part  of  the  system  having 
curved  lines  in  it,  especially  when  the  curved  lines  are  of  metal 
and  the  truss  of  wood. 

Timber  of  any  kind  does  not  expand   or   contract  endwise 
by  change  of  temperature,  or  by  moisture,  or  but  very  little. 

In  fact,  it  matters  not,  how  hydromalic  the  timber  may  be, 
its  length  endwise  changes  very  little  with  change  of  tempera" 
ture,  or  even  saturation . 

Iron,  and  steel  are  both  very  much  affected  by  all  classes  of 
atmospheric  phenomena;  from  the  hottest  weather  of  summer 
to  the  coldest  of  winter,  we  have  a  range  of  about  one  hundred 
and  forty  degrees  Fahrenheit. 

This  upon  a  bar  of  good  iron,  will  change  its  length  about 
one  part  in  twelve  hundred  ;  that  is  to  say,  if  a  bar  of  iron  is 
twelve  hundred  feet  long,  in  the  coldest  weather  of  winter,  it 
will  be  about  twelve  hundred  and  one  (1201)  feet  long  in  the 
hottest  weather  of  summer. 

It  is  therefore  of  the  first  importance  that  all  the  parts  of  the 
bridge,  should  be  so  arranged,  that  whatever  changes  of  tem- 
perature, or  moisture,  or  dryness  takes  place,  either  in  the 
cables,    or  the  suspension   rods,  the  horizontal,  or  vertical  guys, 


u 


or  the  deck  parapets,  they  should  all  expand,  or  contract  a  like 

or  if  they  do  not,  that  they  should  chan<^e  their  length,  due  to 
atmospheric  changes  either  of  heat,  cold,  or  moisture,  in  such  a 
nanner,  as  not  to  impair  the  strength  of  the  structure  in  any 
way. 

This  cannot  be  done,  where  a  perfectly  rigid  horizontal  beam, 
resti'^g  on  masonry  at  either  end,  is  connected  with  the  catenary 
or  chain  in  the  form  of  a  parabola,  which  changes  its  length, 
with  every  change  of  temperature  of  the  atmosphere. 

You  will  readily  see,  how  necessary  it  is  that  the  chains 
should  bear  their  proportion  of  the  load,  however,  distributed 
when  you  realize,  that  under  the  most  farorable  circumstances, 
you  may  expect  a  change  of  at  least  a  foot  in  the  length  of  your 
main  cables,  between  July  and  January,  Now  if  the  deck  is 
made  of  wood  and  rests  on  the  masonry  at  either  end,  it  must 
be  so  flexible,  and  yet  so  stiff  as  to  transmit  its  load,  while  the 
flexibility  permits  the  cables  to  change  their  length  and  yet 
remain  relatively  to  the  load,  on  the  Bridge,  the  same  under  all 
conditions. 

OF    THE    CABLES. 

Three  plans  for  making  the  cables,  have  been  estimated  upon. 
The  first  is  of  steel  plates  or  bars,  twelve  feet  in  length  each. 
These  bars  are  to  lie  edgewise.  They  are  an  inch  and  three  quar- 
ters, (1^  inches)  thick,  and  nine  inches  wide. 

Messrs  Kruppe  of  Essin  in  Rhenish  Prussia,  have  offered  to 
make,  and  deliver  them  at  the  work,  at  thirteen  and  a  half  (13^) 
cents  gold,  duties  paid. 

Their  agent  here,  a  very  mtellitj^ent  gentleman,  well  versed 
in  the  manufacture  of  heavy  steel  shafts,  and  who  is  quite  familiar 
with  the  subject,  assures  me,  that  they  may  be  so  bored  in  the 
eyes,  as  to  be  absolutely  uniform,  and  suggests  as  a  plan  for 
doing  this,  that  they  should  be  so  packed  in  a  room  for  several 
days,  in  such  manner  that  each  plate  will  be  absolutely  of  the 
same  temperature  when  bored,  and  that  thus  they  will  all  be  the 
flame  length  precisely,  and  each  bear  its  own  proportion  of  the 
weights. 


1  I 


25 


quar- 
reu  to 

{\H) 

lersed 
miliar 
In  the 
in  for 
iveral 
l)f  the 
le  the 
If  the 


In  the  construction  of  the  Suspension  Bridge  over  "  Menai 
Straits,"  and  at  "Conway"  and  "Hammersmith  Market  Bridge 
over  the  Thames,"  difficulty  was  experienced  in  so  boring 
the  links  of  the  chains,  that  the  pressure  was  uniform  upon 
the  pintles. 

Messrs  Kruppe  &  Co.  will  undertake  to  remedy  this  difficulty, 
and  their  method  is  to  bore  all  the  plates  under  a  uriform 
temperature. 

I  admit,  that  this  to  a  very  great  extent  relieves  ray  mind  of 
the  anxiety  that  I  have  heretofore  experienced  in  proposing  this 
sy  stem  of  construction. 

The  very  considerable  saving  in  expense,  is  in  favor  of  steel- 
bars  or  chains. 

There  is  however,  another  difficulty  in  this  case,  and  not  a 
slight  one,  arising  from  the  fact  that  in  order  to  secure  the 
greatest  stability  of  the  Bridge,  we  make  tLe  cables  on  the 
saddles,  on  the  tops  of  the  towers,  farther  apart  than  at  the 
centre  of  the  Bridge,  and  hence  the  cables  have  a  horizontal 
as  well  as  vertical  curvature;  now  to  conform  to  this  curve, 
wires  are  much  more  easily  adapted  to  the  case,  under  uniform 
strains  than  bars,  and  pintles,  because  each  series  of  links-  must 
be  bored  in  the  eye  upon  a  line  conforming  to  the  horizontal 
curve, — which  seems  very  difficult  to  do. 

The  doubt  however  has  always  been  in  my  mind,  that  an 
uniform  strain  could  not  by  any  possible  device,  be  assured  in 
every  part  of  the  cable. 

The  very  least  difference  in  the  length  of  one  bar,  by  the  side 
of  another  would  throw  the  strain  irregularly  upon  the  pintles ; 
the  thickness  of  a  sheet  of  paper  would  be  enough  to  strain  the 
printle  unduly,  or  to  give  too  much  or  too  little  to  any  link. 

Hence  I  have  advocated  the  use  of  wires  laid  in  parallel 
strands,  but  if  it  is  certain  that  steel  can  be  used  as  proposed 
by  these  eminent  manufacturers,  it  may  be  well  to  employ  it. 

We  have  not,  however  safficient  data  upon  this  subject  to 
come  to  an  intelligent  conclusion. 

The  strength  of  the  Bridge  depends  of  course  upon  the  cables  ; 
if  every  part  of  the  cable  is  not  exactly  right  and  does  not  bear 


il 


96 


itffdne  proportion  of  the  load,  some  other  part  will  be  unequally 
and  perhaps  unduly  strained. 

The  weight  then  comes  on  the  next  part,  and  gradually  the 
whole  bridge  breaks  away. 

But  if  each  part  takes  exactly  its  own  load,  and  under  all  cir- 
cumstances of  change  of  weather  maintains  that  load,  and  has 
nothing  more  to  do,  than  its  proper  share,  we  should  have  no 
fear  whatever  of  the  structure  lasting  for  centuries,  if  otherwise 
properly  protected. 

The  second  estimate  is  for  Avire. 

It  is  proposed  to  make  four  systems  of  cables,  five  in  each. 

This  will  enable  us  to  distribute  the  load  so  as  to  avoid  any 
horizontal  action  from  the  wind,  and  prevent  vertical  waves : 
cables  all  beinjj  of  the  same  length,  they  will  expand,  and  con- 
tract alike,  and  whatever  changes  of  grade  line  takes  place  in 
the  roadway,  will  merely  be  a  crowning  to  the  bridge. 

If  we  use  wire,  or  steel  bars,  the  load  is  the  same  on  the 
bridge,  with  the  exception  of  the  weight  of  the  material,  itself. 

I  have  estimated,  that  the  Bridge  shall  be  strong  enough  to 
carry  a  train  of  locomotives,  across  its  entire  length,  moving 
at  the  rate  of  thirty  miles  to  the  hour,  and  having  the  roadway 
filled  Avith  passengers  at  the  same  time.  Loading  it  equal  to  two 
hundred  pounds  to  the  square  foot  on  the  highways,  and  three 
tons  to  the  foot  on  the  roadways,  and  tracks,  and  six  times  this 
amount  for  the  breaking  strain. 


THE    EFFECTS    OF     WIND. 
At  the  very  considerable  height  of  this  Structure  above  tide,  it 
is  necessary  to  provide  against  the  unusual  currents   of  wind, 
as  well  as  the  regular  breezes  of  the  river. 

For  many  years  past,  the  Smithsonian  Institute  at  Washington 
has  carefully  collected,  and  collate<l  facts,  which  enable  us  to 
know,  the  exact  pressure  to  the  square  foot  of  the  ordinary  gales, 
and  of  all  the  winds  that  blow  upon  the  continent,  even  to  tor- 
nadoes, that  tear  up  trees,  and  blow  down  houses. 

These  vary  from  a  few  ounces  to  the  square  foot  up  to  forty- 
nine  pounds,  when  it  is  found  that  the  wind  moves  at  the  rate 
of  one  hundred  (100)  miles  per  hour. 


27 

» 

At  pagje  457  Ordnance  Manual  published  by  the  United 
States  Government  for  the  year  1861,  the  pressure  of  the  wind 
is  tabulated  and  we  find  the  following  general   facts. 

One  mile  an  hour,  pressure  hardly  perceptible;  two  or  three 
miles  an  hour   pressure  just  prereptible.     Five  miles  an   hour, 
gentle  wind  pressure  one  tenth  (I-IO)  of  a  pound  to  the  square 
foot.     Fifteen  miles  an   hour  pressure  one  and  one  tenth  (1.1-10) 
pounds  to  the  foot,  and  the  wind  pleasantly  brisk.    Twenty-five 
miles  to  the  hoar,  three  pounds  to  the  foot,  and  wind  very  brisk. 
Thirty -five  miles,  an   hour,  six   pounds  to  the  foot,   high    wind^ 
Forty  miles  to  the   hour,   seven  and   eighty-seven    hundredths 
pounds  to  the  square  foot,  and  wind  very  high.     Fifty    miles  to 
the  hour,  twelve  and  three  tenths  (12.3-10)  pounds  to  the  square 
foot,  and  storm,  or  tempedt.     Eighty  miles  to  the   hour,  thirty- 
one  and  forty-nine   hundredths    (31.49-100)    pounds,   hurricane. 
One  hundred  miles  to  the  hour,  forty  nine  pounds,  and  hurricane 
that  tears  up  trees,  and  carries  away  buildings. 

This  is  recognized  authority,  and  is  probably  as  reliable  as  any^ 
thing  that  exists  in  the  world,  upon  the  pressure  and  velocity 
of  wind. 

In  the  calculations  for  the  strength  of  the  Bridge,  and  the  size 
of  the  various  parts  allowance  has  been  made  for  the  wind  at 
the  highest  known  velocity. 

The   plans  show  the  method  of  sustaining  the  structure   side- 
wise,  and  at  all  times  against  all  currents,  let  them  come  in  any 
direction  that  they  may.  Very  considerable  care  is  necessary  in  so 
arranging  the  parts,  that  if  the  wind,  strikes  the  structure  from 
beneath,  from  above,  or  obliquely  upon  the   side,    that   none   o 
the  parts  are  unduly  strained  so  as  to  cause  rupture. 
But  all  these  forces  are  ascertainable  quantities. 
They  can  be  calculated  with  the  same  certainty,  and  provision 
made  to  resist  them,  as  easily  as  that  of  any  other  known  force 
and  this  has  all  been  provided  for. 

DURABILITY     OF    THE    STRUCTURE. 


You  will  agree  with  me  that  it  is    necessary  that    the  bridge 
shall  be  strong  enough  to  stand  any  load  that  may    ever   come 


I 


! 


■  1 1 


28 


Upon  it,  under  any  circumstances,  or  conditions  ;  and  that  it 
shall  resist  the  force  of  the  wind,  and  be  capable  of  sustaining 
itself  against  the  weight  of  a  train  of  cars  or  herd  of  cattle,  or  of 
as'great  a  crowd  of  people  as  can  get  upon,  and    rush  across. 

And  having  made  the  bridge  strong  enough  to  do  all  this,  let 
us  see  whether  we  have  provided  for  its  durability. 

The  destruction  of  any  material,  if  it  be  of  wood,  or  stone,  or 
metal,  depends  upon  circumstances  that  surrounds  it. 

The  mountains  of  granite  are  gradually  abraded,  and  the  de 
bris  washed  into  the  valleys. 

The  secondary  formations  of  rock,  are  more  readily  acted  up, 
on  by  the  elements. 

Metals  of  all  kinds,  corrode  more,  or  less.  Wood  changes  its 
structure  by  excessive  heat,  cold,  or  continuous  moisture,  and 
all  material  is  more  or  less  perishable. 

But  that  which  is  designated  in  our  language  as    destruction 
arises  from  chemical  changes,  or  mechanical  force :  these  changes 
are  governed  by  well-known  laws. 

*  For  instance  if  a  bar  of  iron,  subject  to  the  action  of  moisture 
and  the  atmosphere  is  said  to  rust,  we  have  simply  in  this  case, 
the  absorption  of  oxygen,  and  the  giving  off  of  hydrogen. 

The  scale  is  an  oxyd  of  iron.  It  is  a  union  of  the  elements,  Ox- 
the  watery  parts  of  the  atmosphere,  with  a  certain  number  of 
the  particles  of  the  iron. 

Now,  when  the  iron  has  taken  up  all  the  oxygen  that  it  is  ca. 
pable  of  holding,  it  will  take  no  more. 

If  the  bridge  is  already  rusted  artificially,  or  covered  with  a 
sufficient  covering  composed  of  rust,  so  long  as  this  remains  in 
it,  it  can  rust  no  more,  if  the  coating  is  thick  enough  to  keep 
out  the  external  air  and  moisture. 

In  order  to  apply  this  practically,  it  is  proposed,  if  strands  of 
wire  are  used,  to  mix  the  ground  ore  of  Franklinite,  which  is  a 
natural  rust,  with  something  to  form  a  covering  and  to  coat 
each  strand. 

It  is  iron  united  with  oxygen.  It  is  the  same  thing  as  the 
rusty  scale  of  iron  would  be,  if  formed  in  the  natural  way,  but 
containing  zinc,  and  other  desirable  metals. 


M 


so 


IS  ca. 


A  paint  of  this  kind  is  to  be  found  in  use  in  the  Niagara  Sus- 
pension Bridge  at  Lewiston,  and  the  St  John  Bridge  over  the 
falls  of  St.  John,  which  has  histed  for  thirteen  years  without  al- 
teration ;  and  it  may  safely  be  predicted,  that  if  the  cables  are 
painted  properly  from  time  to  time,  they  will  last  a  thousand 
years. 

OF    THE    MASONRY. 

You  will  see  by  the  plans,  that  a  very  large  amount  of  ma- 
sonry will  be  necessary. 

Most  of  t\m  must  be  first  class. 

In  order  to  secure  perfect  stability  to  the  towers,  it  is  pro- 
posed that  they  shall  stand  upon  independent  masses  of  masonry, 
resting  on  the  natural  rock. 

This  rock  as  has  been  before  stated  is  the  primary  formation 
of  columna  granite.  The  retaining  walls  about  the  approaches 
need  not  be  of  such  costly  work. 

The  towers  are  to  have  cut  joints,  and  builds,  and  the  whole 
is  to  be  laid  in  hydraulic  cement.  The  upper  courses  must  be 
doweled,  and  bolted  together,  and  it  will  probably  be  found 
best  to  do  this  with  copper  rods  passing  through  at  least  two 
or  three  courses. 

In  the  estimates  I  have  divided  the  masonry  into  three  classes  ; 
first  the  foundations  ;  second  the  retaining  walls,  and  third  the 
towers. — These  are  again  subdivided   according  to  the  kind  of 
face,  they  are  to  have,   rock  faced,  scabble  work,  hammer  dress- 
ed &c. — The  Anchor  masonry  is  distinct  of  itself. 

The  tops  of  the  towers  will  be  fine  cut,  the  rest  of  the  towers 
is  rock  faced  with  aris  lines  in  the  joints. 


the 
but 


THE    SADDLES. 

In  order  to  provide  for  the  change  of  length,  that  wiU  take 
place  by  the  expansion,  and  contraction  of  the  back-stays,  or 
that  portion  of  the  cables,  which  is  between  the  anchors,  and 
tops  of  the  towers,  a  system  of  horizontal,  steel  rollers  is  to  be 
inserted,  between  two  plates  of  cast  iron. 


;l!i 


:;'! 


do 


The  lower  one  of  which  will  rest  upon  a  lead-plate  on  the  top 
of  the  masonry  of  the  towers. 

The  upper  one  is  above  the  steel  cylinders,  and  is  called  a 
saddle,  the  top  of  which  will  be  the  segment  of  a  circle,  termin- 
ating in  tangent  lines. 

If  no  provision  were  made  for  a  motion  upon  the  tops  of  the 
towers,  the  lines  offeree,  would  be  thrown  off  the  vertical  axis 
of  the  tower,  the  tendency  of  which  would  be  to  upset  tlie  ma- 
sonry and  tear  it  apart. 

The  cylinders  referred  to,  between  the  plates  of  cast  iron, 
with  steel  faces,  will  prevent  any  action  of  this  kind. 

Just  enough  to  compensate  for  the  expansion,  or  contraction 
of  the  back-stays  so  that  in  all  cases,  the  forces  will  be  vertical 
upon  the  tower. 

It  has  been  necessary  in  some  bridges  to  make  towers  inclin- 
ed, where  there  was  not  room  to  extend  the  back-stays  a  suffi- 
cient distance  to  the  rear. 

You  have  no  difficulty  however,  of  this  kind  in  your  locations ; 
the  towers  will  be  plumb,  and  all  the  forces,  resulting  from 
the  load  on  the  Bridge,  the  weight  of  the  Bridge,  itself,  and 
anything  that  may  be  upon  it,  will  be  directly  vertical,  and 
through  their  axes. 

All  the  masonry  of  the  foundations  and  towers  must  be  so  laid, 
that  the  stones  will  receive  the  force,  perpendicular  to  their 
natural  beds. 

The  weight  on  the  stones,  tending  to  crush  them,  has  been 
put  at  very  much  less  than  they  will  sustain,  the  object  being  to 
make  a  large  mass  of  masonry  to  resist  vibrations. 

A  new  system  of  taking  up  the  slack  of  the  horizontal  wind 
guys,  has  been  contrived  which  is  very  simple,  and  will  doubt- 
less be  found  effectual  ;  it  is  shown  in  the  drawings. 

On  the  whole,  you  may  rely  on  the  foundations,  upon  the 
strength  of  the  Bridge,  and  its  durability  as  being  all  that  can 
be  reasonably  desired . 

It  is  fortunate  for  us  that  scientific  inquiry  has  settled  beyond 
question,  everything  that  we  have  to  deal  with,  in  building  a 
bridge  so  far  as  forces  are  concerned. 


_     i:  >A. 


81 


All  such  problems  as  the  direction,  and  quantity  of  force 
exerted  at  any  point,  and  the  nature  of  this  force,  together  with 
the  ability  of  given  materials  to  resist  any  forces  either  of  twist- 
ing, with  which  we  have  but  little  to  do,  or  with  compression, 
or  extension  ;  all  these  are  well  defined  beyond  dispute,  by  the 
rules  for  determining  the  composition  and  resolution. 

If  we  were  compelled  to  entei  the  field  of  speculative  philoso. 
phy,  to  inquire  into  the  correlation,  or  the  conservation  of  forces, 
Doctors  may  be  found  who  differ. 

With  these  differences  we  have  nothing  whatever  to  do  in 
building  a  bridge,  however  desirable  they  may  be  to  investigate 
for  other  purposes. 

I  had  prepared  some  general  remarks  upon  the  methods  to 
be  employed,  to  determine  the  best  kind  of  materials  for  use, 
such  as  stones,  cement,  wood,  iron,  and  steel,  together  with  in- 
quiries into  the  nature  of  these  materials,  and  their  manufacture, 
and  analysis,  but  as  the  paper  has  already  grown  into  perhaps 
undue  proportions,  and  as  all  such  nmtters  would  apply  equally 
to  any  location,  you  may  select,  and  to  all  similar  cases,  I  shall 
hope  to  present  them  for  your  consideration,  when  you  have 
determined  the  general  location,  and  settled  whether  you  will 
have  a  single  or  double  track  bridge,  and  whether  you  will  in- 
clude public  highways  as  well  as  Railways,  or  not,  and  what 
maximum  gradients  you  will  permit  for  the  approaches. 

The  following  is  a  table  of  the  Ratios'  of  Strains,  and  quanti- 
ties at  thr  five  selected  localities ;  the  section  at  C.  C.  being 
unity. 

These  are  easily  counted  into  prices  and  cost,  when  you  de- 
termine upon  any  locality. 

1st.  Shall  there  be  highways':* 

2nd.  Shall  there  be  a  doable,  or  single  line  of  railway  ? 

3rd.  The  maximum  grade  of  the  approaches. 


9 

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As  very  much  has  been  said,  in  the  vicinity  of  the  work,  about 
the  practiciibility  of  a  railway  connection  from  the  E.  E'.  loca- 
tion to  Peekakill,  cro.-sing  the  mountains  east  of  St  Anthony's 
Nose,  through  the  pass,  now  used  by  the  Peekskill,  and  Garri- 
son's higliway,  I  have  run  an  aneroid  line  over  it,  and  find  it  to 
be  impracticable  with  sixty  feet  grades,  without  making  a  tun- 
nel, I  should  judge  a  mile  long. 

The  pass  is  about  four  hundred  and  twenty-five  lieet  above 
tide,  and  the  grades  without  a  tunnel  would  be  about  one  hun- 
dre<l  and  thirty  feet  to  the  mile. 

In  order  to  preclude  the  possibility  of  any  doubt,  in  regard  to 
the  eagle  valley  pass,  west  of  West  Point,  I  ran  a  barometrical 
line  of  levels,  and  found  the  gap  at  the  head  of  Buttermilk  Brook 
to  be  over  eight  hundred,  and  twenty  feet  above  high  tide. 
These  were  mere  precautionary  measures,  and  add  to  your  cer- 
tain knowledue  of  the  ground,  important  data. 

You  will,  I  believe,  see  by  these  investigations,  that  all  the 
railway  interest  so  far  as  connecting  with  the  bridge  is  concern- 
ed, have  been  considered. — The  Hudson  Kiver  Rail  Road  can 
form  connections,  the  West  Shore  the  same,  the  Midland  can 
come  upon  it,  the  Boston,  Hartford,  and  Erie,  and  the  Dutchess, 
and  Columbia  by  the  line  of  the  Erie,  and  New  England,  and 
the  Fish  kill  Branch,  and  in  fact  all  existing  or  contemplated 
lines,  can  be  accomodated. 

Trusting  that  these  facts,  here  presented  will  give  you  such 
information  as  you  require,  I  have  the  honor  to  be  very  i^espect 
fully, 

Your  Obedient  Servant, 

EDWARD   W.  SERRELL, 

Engineer  in    Chief. 


Printed  by  order  of  the  Board  for  the  use  of  th?;  members , 

James  H.  Jenkins, 

Secretary. 


